during the Combination of Acids and Bases. 233 



is not pure water, but a weak solution of nitrate of potash, which is actually 

 heated ; and the above numbers would therefore require a further correction, in 

 consequence of the difference between the specific heats of these liquids. This 

 correction, however, must be extremely small, from the very dilute solutions 

 obtained : it would probably be within the limit of the errors of observation. 



16. Many of the subsequent experiments would have been performed with 

 difficulty in a metallic vessel. I therefore substituted a pretty thick glass jar for 

 the brass vessel, and both solutions were brought as nearly as possible to the tem- 

 perature of the surrounding air, at the commencement of each observation. In 

 this way, numerous experiments were easily performed, which yielded results 

 comparable with each other, although all below the truth. It was, therefore, 

 necessary to ascertain the absolute loss of heat when the experiment was per- 

 formed in this way, and whether it was proportional to the elevation of tem- 

 perature. For this purpose, solutions were prepared containing the same quan- 

 tity of potash and nitric acid as in the experiments with the brass cylinder. 



17. Alcaline solution 27 gr., containing .0882 gr. potash ; acid solution 3 gr., 

 containing 1.06 nitric acid. 



Temp, rose on mixture, 1°.45. 

 Another experiment gave 1°.45. 



18. Alculine solution 27 gr., containing .1765 potash ; acid solution 3 gr., 

 containing .212 nitric acid. 



Temp, rose on mixture 2°.90. 

 Another experiment gave 2°.95. 



19. Alcaline solution 27 gr., containing .353 potash ; acid solution 3 gr., 

 containing .424 nitric acid. 



Temp, rose on mixture 5°.8. 

 Another experiment gave 5°.8. 



20. Alcaline solution 24 gr., containing .353 potash ; acid liquid 6 gr., 

 containing .424 nitric acid. 



Temp, on mixture rose to 5°.9. 



21. Collecting these results, we obtain for the elevation of temperature of 

 VOL. xix. 2 H 



